"The countries in the Middle East have welcomed millions of refugees, first Iraqis and now Syrians. The massive influx of refugees to these countries has stressed their national health systems at all levels," said the report in The Lancet medical journal.
Help from international organisations and donors has not been enough, and the cost burden "has disproportionately fallen upon the host governments," it said.
Jordan, for example, paid about $53 million (39 million euros) for refugee medical care in the first four months of 2013.
The paper said the world's response to humanitarian crises was largely based on experiences in refugee camps in sub-Saharan Africa, where infectious diseases and malnutrition were the main concerns.
In middle-income countries, levels of chronic diseases like cancer are higher -- and costlier per individual to treat.
Study author Paul Spiegel, the chief medical expert for the UN High Commissioner for Refugees (UNHCR), called for "innovative financing schemes" to help.
"It could range from a fund that individuals and organisations could donate into, to health insurance or social schemes that exist for nationals in the host country," he told AFP by email.
"Refugees sometimes have livelihood opportunities and can pay for themselves, other times it could be UNHCR or other organisations."
The UNHCR recorded 35.8 million displaced people in 2012, according to the report, including 10.5 million refugees and 17.7 million internally displaced people.